Isotonic dextrose and isotonic saline as solvents for intravenous treatment of premature labour with ritodrine

Summary

Ritodrine was given intravenously on 38 occasions to 36 pregnant, non-diabetic women admitted with preterm labour. Isotonic (5 per cent) dextrose and 0·9 per cent saline were used as solvents for ritodrine, and the patients were allocated dextrose or saline at random.

Glucose, bicarbonate and potassium in plasma were measured before the treatment started and after 3 and 6 hours infusion. Plasma glucose increased by 3·56±0·55 (s.e.) in the dextrose solution group and by 2·39±0·45 mmol/I in the saline group. Bicarbonate decreased in both groups independent of the solvent used, by 2·5±0·60 and 2·4±0·52 mmol/l, respectively. A positive correlation was demonstrated between the dose of ritodrine given and the degree of acidosis. Plasma potassium decreased more in the dextrose solution group, by 0·7±0·1 mmol/l, than in the saline solution group (0·5±0·1 mmol/l).

It seems reasonable to administer ritodrine dissolved in isotonic dextrose, because the ketoacidosis induced is similar whether dextrose or saline is used, and the infusion of saline might involve a risk of overloading.